Validation :: API framework technical principles in the Java class library (Exploration of the Technical Principles of Validation :: API Framework in Java Class Libraries)
VALIDATION :: API framework technical principle exploration in Java class library
Overview:
When developing Java applications, data verification is one of the important steps to ensure the integrity and reliability of data.Validation :: API framework in the Java class library provides us with a powerful tool that can easily verify and verify data.This article will analyze the technical principles of Validation :: API framework in the Java library, including its working principles, core concepts, and code examples.
1. Validation :: API framework working principle:
Validation :: API framework is a powerful tool for data verification in the Java class library.Its working principle can be divided into the following steps:
-D definition verification constraints: We first need to define verification constraints by annotation or programming. These constraints are used to guide the value of validation :: API framework for data verification.
-Coly build a validator: Validation :: API framework to perform actual data verification by the verification device.We can build a verification device through value :: Builder, and then pass the data to be verified to the verification device.
-Exical data verification: Once the verification device is constructed, we can use it to perform data verification.The verification device will check the data according to the verification constraints we define and generate the corresponding verification results.
-The processing results: Validation :: API framework encapsulates the verification results into a collection of the Constraintviolation object. Each constraintvilation object represents a constraint of a failure of a verification failure.
2. Validation :: API framework core concept:
When using Validation :: API framework, there are several core concepts we need to understand:
-The constraint: Validation :: API framework defines a series of constraint annotations for verification, such as@notnull,@min,@max, etc.We can restrict the attributes of various data types through these annotations.
-Cocular interface: Validation :: API framework provides a Validator interface. We can implement this interface to define data verification logic.
-Che Validation: Validation :: API framework creates a verification factory factory through the ValidatorFactory class.The verification device factory is responsible for creating and managing instances of verification device.
-The constraint verification device: The constraint of the school inspection device is the specific implementation of the verification device, and the data verification is responsible for the constraints of our definition.
3. Validation :: API framework code example:
The following are code examples of Validation :: API framework to help you better understand its usage methods and technical principles:
-Add using annotation definition verification constraints:
public class User {
@Notnull (Message = "Username cannot be empty")
private String username;
@Min (Value = 18, Message = "Age must be greater than or equal to 18 years"))
private int age;
// omit other attributes and methods
}
-Colon the verification device factory and verification device:
ValidatorFactory factory = Validation.buildDefaultValidatorFactory();
Validator validator = factory.getValidator();
-Exical data verification:
User user = new User();
user.setUsername(null);
user.setAge(17);
Set<ConstraintViolation<User>> violations = validator.validate(user);
for (ConstraintViolation<User> violation : violations) {
System.out.println(violation.getMessage());
}
In the above code example, we define the verification constraints of the user class attributes through annotations.We then created a verification factor factory and an actual verification device.Finally, we pass the USER object to the verification to the verification device and traverse the verification results for processing.
Summarize:
Validation :: API framework is an important tool for data verification in the Java class library.By exploration of the technical principles of Validation :: API framework, we understand its working principles, core concepts, and methods of use.By using Validation :: API framework reasonably, we can easily perform data verification to improve the integrity and reliability of data.
